1. Field of the Invention
This invention relates to power transmission belts with at least one friction drive surface and, more particularly, to a power transmission belt having short reinforcing fibers that project from the at least one friction drive surface.
2. Background Art
Modern automobile engines are designed to allow quick changes in rotational torque, thereby to improve fuel efficiency, power, and other performance characteristics. As a result, heavy loading may be applied to a power transmission belt, typically with a V-ribbed construction, that cooperates with engine accessories. Heavy loading on such belts tends to generate stick-slip noise. This noise may be intensified when the belt gets wet, as when exposed to environmental water, or the like.
It is common to paint pulleys used with belts in the above types of systems to prevent rust formation, as before the automobile is delivered to a user. The paint is typically weakly adhered and is intended to fall off, as during simple idling, in a relatively short period that may be on the order of twenty to thirty minutes. This paint may not completely fall off of the pulleys after such limited operation. Any residual paint on the pulleys tends to become sticky at high temperatures. This condition may be the cause of additional stick-slip noise generation between the cooperating pulleys and belt.
Various approaches have been taken to avoid stick-slip noise generation by producing a belt with a low coefficient of friction between the belt and cooperating pulley surfaces. In Japanese Utility Model Publication No. 31006/1995, short reinforcing fibers are embedded in the compression section of a belt and project from the friction drive surfaces thereon. A powder viscosity depressant, such as talc, is applied so as to substantially entirely cover the projecting parts of the fibers.
While this approach reduces the frictional coefficient between the friction drive surfaces and pulleys due to the coverage of the projecting parts of the reinforcing fiber by the talc, the talc has a tendency to fall off as the belt is operated. Thus, the benefits of the talc may be realized for only a relatively short time period.
As an alternative approach, as disclosed in Japanese Patent No. 3440288, a powder surfactant is rubbed onto friction drive surfaces where they contact cooperating pulleys.